Macular degeneration is the imprecise historical name given to a group of diseases that cause sight-sensing cells in the macular zone of the retina to malfunction or lose function and results in debilitating loss of vital central or detail vision.
The retina contains an extraordinary photosensitive array of cells that line the back of the eye. The light falling onto these cells in the retina is transformed into electrical signals that are transmitted to the brain centers that process and interpret them.
The most concentrated collection of photosensitive cells in the retina, including those that enable critical color and fine detail vision, are found in the Bulls-Eye center zone in an area called the macula.
Macular degeneration can cause different symptoms in different people. Sometimes only one eye loses vision while the other eye continues to see well for many years. The condition may be hardly noticeable in its early stages. But when both eyes are affected, reading and close up work can become difficult.
A case of adult macular degeneration is diagnosed every three minutes in the United States of America. One in six Americans between the ages of 55 and 64 will be affected while one in four Americans between 64 and 74 will be stricken. One in three over the age of 75 will be affected. Each year 1.2 million of the estimated 12 million people with macular degeneration will suffer severe central vision loss. Each year 200,000 individuals will lose all central vision in one or both eyes.
The only proven treatment is laser photocoagulation, but only 10–15% of eyes with wet macular degeneration are treatable with laser. Then recurrences after laser treatment are common (70% in 5 years). The average visual acuity 3 years after treatment is usually 20/200 to 20/250.
Patients rarely lose all of their vision from macular degeneration. Though they have poor central vision, most can walk around, dress themselves, and perform many of their normal daily tasks.
In order to facilitate some of the normal daily tasks of people with macular degeneration, several vision enhancement systems have been developed. These systems usually include some type of a video camera and a monitor. The user moves a book or magazine or picture underneath the camera, and the item shows up on the monitor.
The problem with these systems, however, is that they are prohibitively expensive and hard to maneuver. Some systems have portable headset systems and cost several thousand dollars. Others are very inexpensive, but require the user to move the item of interest underneath the camera, which can be unnatural and hard to learn.